We said that the Earth rotation axis is tilted 23.5 degrees to its orbital plane around the Sun,
that is, to the ecliptic, the path of the Sun due to the Earth’s annual motion around the Sun.
And we said the reason the Earth stays tilted to its orbit is that the Moon’s orbit around the
Earth holds the tilt in place. We said this creates the seasons and allows for life on Earth to be
abundant, diverse, and stable because it prevents extreme hot or cold. We would like to go into
this in depth because in the previous section we found reason to suggest the Earth/Moon/Sun
system is technology that may be geared towards the success of life.!
If the earth is tilted towards the Sun by 23.5 degrees this is summer and if it is tilted away by
23.5 degrees this is winter. At fall and spring equinox the Earth is tilted neither towards or away
from the Earth. However, the seasons are more extreme as you move North of the equator.
Because the equator is only 23.5 degrees above or below the ecliptic, the plane of its orbit, it is
always facing the Sun so within this region, 23.5 degrees North of the equator and 23.5
degrees South of the equator, the Sun is always high in the sky at noon, meaning there is little
difference between summer and winter. Even the days are always approximately equal in
duration to the nights. They are both 12 hours long. This is a region called the Tropics. As you
travel North or South of the Tropics the seasons become more notable. When the Earth is
inclined towards the Sun it is summer in the Northern hemisphere and winter in the Southern
hemisphere where it is pointed away from the Sun. When the Earth moves around to the other
side of the Sun, the Earth is tilted away from the Sun in the Northern hemisphere but is tilted
towards the Sun in the Southern hemisphere and it is summer. Depending on your latitude
above or below the equator and the time of the year (the Earth’s position with respect to the
Sun in it its orbit) determines how high the Sun is in the sky during the day and thus amount of
sunlight you get and the season. The time of year determines in these latitudes the hours in a
day and the hours in a night. So at higher latitudes North or South of the tropics means in the
summer you can have 16 hour days with 8 hour nights in the Northern latitudes. Or, in the
winter 8 hour days with 16 hour nights. In fact in the Arctic and Antarctic it is daylight for 6
months and night for six months.!
We can determine the intensity of sunlight given the time of the year and your latitude. On the
summer solstice, the Sun is directly overhead at noon 23.5 degrees above the equator (The
Tropic of Cancer, or Northern Tropic). Your latitude minus this angle is your solar angle, the
degrees the Sun is below the Zenith (see illustration next page) or the height it is in your sky at
noon. The cosine of this angle reduces the intensity of the Sun giving its value for your location
at this time. On winter solstice your solar angle is your latitude plus 23.5 because the Sun is
now overhead at noon 23.5 degrees below the equator (The Tropic of Capricorn, or Southern
Tropic) and the intensity of the Sun is reduced by the cosine of this angle.!
For our purposes, since we are suggesting The Earth/Moon/Sun system is technology, and that
the Moon holds the Earth at 23.5 degrees to the ecliptic, then if this angle is significant as part
of the technology, we want to ask: At what latitude is agriculture (which provides sustenance
for life) optimized? Of course we have different soils at different latitudes, different amounts of
sunlight and seasonal variations, but history answers the question, actually archaeology. We
ask at what point did humans settle down from following the herds and hunting with stone
spearpoint, and invent agriculture, mathematics, smelting, government, and writing. The
answer is in Mesopotamia (Sumer) twelve to fourteen thousand years ago. This was part of the
fertile crescent which spans from Egypt to Turkey where there are many archaeological sites
showing the beginning of agriculture. Scholars put the fertile crescent at latitude 33.7 degrees
though it can be as far South as Egypt or as far North as Turkey. We have for the solar angle
and intensity of sunlight at this latitude:!
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